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Clutching Woes!

Itís been almost a year since our Caterham has put wheels on the street. Last June while driving the Seven home on my evening commute through the 91 Freeway work zone in downtown Riverside, traffic predictably came to a halt. I pushed in the clutch pedal and tugged on the gear lever, and the lever would not budge! What the *%&$@! I tried again and pulled really hard and this time got the gearbox into neutral. One problem solved, but a much larger problem loomed: what to do when traffic began the usual stop and start crawl? Due to the construction on this section of freeway, there was no shoulder. In a mild panic, I pushed in the clutch and was able, with loud noises of protest from the gearbox, to engage third gear. Using this, I got to an off-ramp, and with only a few intersection infractions later, made it home.

At first I thought the clutch master cylinder had failed and would not hold the clutch open. I had re-built the cylinder about 40,000 miles earlier and was suspicious of its condition due to a few earlier instances at stop lights where it was hard to get the car into first gear. Not an uncommon occurrence with clutch hydraulics. So I bought a new Girling cylinder from Summit Racing and installed it. For a brief moment I thought success, but a quick drive around the block proved me wrong. Major surgery was now indicated.

With the engine and trans pulled out of the chassis, I unbolted the bellhousing from the engine, and laying in the bottom of the bellhousing was my first piece of evidence; a short and twisted piece of heavy spring steel. Next I unbolted the pressure plate from the flywheel and there in all its dusty ground up glory lay the remainder of one of the clutch disc cushion springs. It had migrated out of its clutch disc holder. Not surprisingly, the opposite spring was just about ready to join it. The clutch disc and pressure plate were OEM Ford parts. At this point, they had also been in service for about 40,000 miles, admittedly including several AROSC enduro races and a number of other track events.

The last time I replaced the clutch, Jon Nelson at Caterham USA advised that I should have taken the opportunity to upgrade to a lighter flywheel. So now, this was my opportunity and I gave Jon a call. Jon is no longer the US distributor, but he said that he still has considerable inventory of Caterham parts in his garage warehouse. He suggested I check to see if Fidanza still manufactures a flywheel for the Zetec, but mentioned there were some dimensional issues when fitting one to a Zetec with flywheel/clutch sourced from the Ford Contour parts bin. I found the Fidanza flywheel, part no. 186991 and ordered one, and like Jon warned, the starter ring was in a slightly different plane than the steel flywheel that I had been using. However dimensionally, the timing ring was positioned okay, and the clutch mounting face was the same. Another call to Jon and he happened to have a starter that will work. Success!

Because this was the third time Iíve had a Ford OEM clutch failure, I wanted to upgrade to something more robust. I found Clutch Masters, located in Rialto, only a few minutes away from my home in Riverside. These guys know their business, and when I took my old clutch assembly to them, they pointed out several things that caused the problems. Most significantly, it was the design of the diaphragm finger ends for interfacing with the center shaft throw-out bearing. The ends of the fingers should be a raised curve, and not cut straight. I ordered a Stage 1 racing clutch from them and luckily the stack-up from the flywheel is identical to that of the OEM assembly. No shimming is necessary for the throw-out bearing.

Finally, this seemed like a good occasion to replace the flywheel retention bolts. I ordered a set from Automotive Racing Products (ARP). They have twelve point heads and fit perfectly onto the flat mounting area of the Fidanza flywheel (something the stock bolts heads were too large for). Now I have all the necessary parts for the upgrade and the re-build has begun. The journey back to life!

Slow start, but the new flywheel, clutch disc and pressure plate are installed on the Zetec. However I had some problems trying to install the transmission last weekend. I think the problem was a slightly misaligned clutch disc. I could not get the transmission to mate with the engine block. Yesterday evening on a hunch, I wondered if the pilot bearing was damaged, so I took a look. The bearing was fine, so I tried inserting the pilot tool and it would not seat all the way. So off came the pressure plate; put the pilot shaft through the clutch disc and it would seat completely home. I then re-installed the pressure plate and now I believe it's all perfectly aligned. We'll see next weekend when I make another attempt to mate the transmission to the engine. Really, I tell myself, this should not be this hard! What could be easier than joining a transmission and engine when they are both out of the chassis?

Hi Doug,
Good to hear from you! I will attempt a fusion this next weekend. I think it will work, but that could just be wishful thinking. Last time I replaced the clutch and flywheel, I lined things up by eye - and it worked! If my attempt this weekend isn't successful, I'll take you up on the input shaft tool. That's really the best you can get short of emptying the bank for the Snap-On adjustable tool.

As the clutch and flywheel upgrade for our Zetec powered Caterham has progressed, I’ve been amazed at the challenges. Solve one thing and something else pops up! The latest was a clutch disc misalignment (or maybe not) and my inability to mount the transmission to the engine. So I checked and re-centered the clutch disc and the alignment tool now would fully bottom out when inserted in any rotational position. My frustration still ran high though; the transmission still would not mount home to the engine. That’s when the aluminum filings on the top starter ring gear teeth caught my attention.

A close look inside the bellhousing quickly showed the problem. The starter ring teeth were digging into the bellhousing aluminum when I attempted to tighten the mounting bolts. To check this, I removed the bellhousing from the transmission and tried mounting it. That was it! The first half-inch of the bellhousing was machined for the steel flywheel, and then the interior shape angled medially. The Fidanza flywheel starter ring plane is slightly aft of the plane for the steel flywheel, about 3/8 inch. Machining the interior bellhousing to the same radius as the steel flywheel, about a half inch deeper fixed this.

Finally, this weekend I re-attached the bellhousing to my T-9 transmission and mounted the whole assembly to the engine. Success! Next weekend, with some help, I’ll stuff the drivetrain back into the chassis and begin hooking up the electrics and plumbing. The end is in sight and summer morning drives beckon.

Okay, we're getting close now! Today, this afternoon I picked up the two T-9 gearboxes with new seals and other refurbishments. One has the bellhousing attached and the other will go on a shelf as a spare.

I'll back up a bit first. In October, the engine and one of the gearboxes were installed in the chassis and everything seemed to look and work good. Or so, at first, I thought. First gear, second gear, third gear, and fourth gear worked great for a few laps around the block. Patting myself on the back for a job well done, I thought let's go for a drive to Lake Mathews and get some exercise. We headed out and with a little more speed on a back road, no fifth gear! No grinding or anything, the shifter just would not go through the gate. I contacted Jon Nelson and he gave me a few thoughts and ideas to try, but still no fifth gear. Once again, I decided to pull the drivetrain out for gearbox diagnostics. An old slalom racing friend at a local shop removed the small side-plate on the tail shaft housing and like magic, we had fifth gear! This plate's mounting holes are slotted and it provides a stop for the fifth gear shift rod. It had been installed a little too close during a previous re-assembly (for a synchro replacement). Lesson learned.

One more thing. The T-9 gearbox has a shift rod for second and third gears that protrudes through the front of the gearbox and into a recess in the bellhousing. I've been plagued with oil leaks from these gearboxes for years. I wasn't sealing the bellhousing/gearbox interface, and thus the leaks! Another lesson learned. My mechanic friend suggested using an anaerobic sealer in this interface, similar to the sealer used on the differential rear plate. Makes sense.

Hopefully, family obligations permitting over the holiday, I'll make some progress re-assembling our Seven again! Getting the car back on the road will be a great Christmas present! So.....

He sprang to his sleigh, to his team gave a whistle,
And away they all flew like the down of a thistle.
But I heard him exclaim, 'ere he drove out of sight,
"Happy Christmas to all, and to all a good night!"

I ran into the same transmission leak on my Birkin. When I originally assembled the gearbox and bell housing, I found hat that paper gasket wouldn't fit due to the spacer circumference for the throw out bearing. I blew it off as I thought that there was no fluid pass through. I didn't discover the leak until a couple of weeks after I filled the gearbox. I ended up removing the drivetrain and cutting the paper gasket to fit and used a generous amount of gasket sealant ( the grey stuff used for the front cover) taking care to seal the shifter rod pass through well. This was an oversight in the Birkin assembly manual that I brought to Tom Carlin's attention. Now I am accumulating dust under the drivetrain. Now if I could only get the ECU sorted out.

Okay, we're getting close now! Today, this afternoon I picked up the two T-9 gearboxes with new seals and other refurbishments. One has the bellhousing attached and the other will go on a shelf as a spare.

Clark

Do these have the correct input shaft length? Mine uses the longer of the two common lengths, I believe there may be a third.

Hold on to those extra T9s as they are becoming scare. If you want one from SPC you need to provide a core.

Good to hear from you! Measuring from the machined surface on my transmissions, my input shafts extend 8 1/8" to their tips. The configuration for my car uses a slightly different clutch T/O bearing adapter than the one shown in your photo, but otherwise they appear to be identical. Also, I believe that the splines on my input shafts are longer the those on the shaft in the right of your photo. Right now I cannot see their extent due to the T/O adapters being installed on both transmissions.

One of my T-9's came from Jon Nelson with my car and the other was originally supplied with Magnus' car from Mr. Sours. I bought Magnus' gearbox as a spare after he'd installed the Caterham 6-speed trans in his car. Later, I installed it when the 3rd gear synchro failed in my car's original transmission.

So much for planning! Most of this past week was consumed with reducing my household chores list, but today while it rained I had the opportunity to connect the engine and transmission, install the starter motor and generally get things ready to insert the drivetrain back into our Seven's chassis. I'll do that as soon as I can round up some help! Finally a twinkle of daylight is beaming through at the end of this project's tunnel.
- Happy New Year!

It was a longer journey than I wanted, but our Caterham is back logging road miles again and running better than ever! I'm learning all over again why driving a Seven is such an incredibly hilarious experience; i.e. "shit eaten' grin from ear to ear". (This quote is from a long ago conversation with Joe Kelly, E/P Caterham racer and friend of Michael Bedard).

Best wishes,

Last edited by Clark; March 9th, 2017 at 08:22 PM.
Reason: Remembered something!

Over the past 20 years or so, I've noticed that lots of Zetec powered Caterhams have clutch related failures. Has anyone considered measuring the concentricity of the bellhousing to the engine? It is common with aftermarket bellhousing for there to be small machining errors resulting in the transmission input shaft not being perfectly centered when inserted into the pilot bearing. This can create loads on areas like the clutch leading to early failure. If anyone has run into this, please contact me.
John

I have a Zetec powered Caterham but mine uses the Crossflow to Zetec conversion bellhousing. No clutch issues so far at about 30K miles. I helped M. Murphy with an issue on his Zetec powered Caterham and found the annular throwout bearing bell housing was misaligned. There are two alignment holes in the bellhousing that were oversized for the pins from the engine block. The bushings were left out either by oversight or intentionally. See photos of with and without the bushing. I suspect the bushings were left out to fudge the position and keep the ring gear away from the bellhousing instead of fixing it correctly.

I installed some oilite bushings and had to grind off some of the bellhousing where the ring gear hit. Maybe some of the area around the starter too.

In any case as I remember the issues with the alignment were solved. At least Murphy hasn't asked for his money back.

Perhaps others were installed the same way, i.e. without the bushings???

In the first photo you can see where the ring gear was dragging on the bellhousing. This area was ground out to clear after the bushings were added.

I am running an Exedy lightened flywheel on my Duratec. I found that I had to use the starter from a Focus rather than the Ranger starter that I had as the ring gear spacing is slightly different. Could that be the same sort of issue on the Zetec?

I don't think the ring gear was part of the problem, I think it might be the misalignment but we still have limited responses on the clutch failures.

As far as the ring gear spacing, I have a stock Zetec lightened flywheel. I bought a Fidanza flywheel when I upgraded to the Zetec SVT and to my chagrin the ring gear was on the opposite side of the flywheel. Of course this was two days before leaving for a track day and no quick option to get a stater that would work with the Fidanza.

I fobbed the Findanza off on Murphy at a good price so not a total loss.